Why do kids yell Marco polo?

Answer 1

Marco Polo is also a popular children's game played in a pool. The child who is "it" must swim around the pool with his eyes closed, attempting to tag the other players. The "it" child can only sense where the other players are by calling out "Marco!," at which point all the other players are required to yell "Polo!". By judging where the sounds are coming from, the child who is "it" is able to overcome his self-imposed blindness and hopefully tag somebody else, who then becomes "it." There are other rules to this game, varying from region to region (see 'fish out of water[?]').